An overview of soft-switching technique for flyback converters

Flyback topologies are widely used in low power applications due to the small size and low cost. To improve the efficiency via reducing the switching loss, valley switching technique is introduced and several methods to realize valley switching are analysed and compared. Besides, the matter of frequency under light load condition is described, which can be solved by valley skipping technique, whereas resulting in some extra issues caused by frequency hopping simultaneously. Consequently, various solutions to the frequency hopping are presented and analyzed.